1. Field of the Invention
The present invention relates to an exposure method and exposure apparatus used in forming fine patterns of semiconductor devices or liquid crystal displays.
2. Related Background Art
With progress of semiconductor fabrication techniques, integration rates of semiconductor integrated circuits have been improved heretofore. The resolution of projection exposure needs to be enhanced in order to improve the integration rates. The resolution depends upon the wavelength of exposure light and the numerical aperture of projection optical system. Namely, the resolution increases with decreasing wavelength (.lambda.) of exposure light or with increasing numerical aperture (NA).
The wavelength of exposure light used in recent projection exposure apparatus comes to be as short as that of the excimer laser, and the numerical aperture is approximately 0.5.